Optimizing video clarity

ABSTRACT

Described herein are techniques and mechanisms for optimizing video clarity. According to various embodiments, a plurality of requests from client devices to access a media content item for playback at the client devices may be received at a server. Each of the client devices may have associated therewith device characteristic information that describes one or more characteristics of the client device. A device characteristic that describes a portion of the client devices may be identified. The portion of the client devices may meet a threshold value for creating a media content encoding item. A media content source item corresponding to the requested media content item may be transcoded to create a media content encoding item. The media content encoding item may be encoded to match the identified device characteristic.

TECHNICAL FIELD

The present disclosure relates to the encoding of video content forpresentation on content playback devices.

DESCRIPTION OF RELATED ART

Content such as television programming and movies may be provided tousers via various types of services such as television networks andon-demand content providers. Content transmitted to client devices forplayback may be encoded using various types of encoding options. Forinstance, some content may be encoded at a relatively high resolution,while other content is encoded at a lower resolution. Some types ofencoding, such as higher resolution encoding, may require more bandwidthfor transmission. However, an encoding may offer a relatively worseviewing experience if, for example, the encoding does not match thecapabilities of the device at which the content is presented. Forinstance, content may be encoded at a video source frame size that failsto match the device screen size, which may result in a presentation ofvideo with a “fuzzy” appearance on the device.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, whichillustrate particular embodiments.

FIG. 1 illustrates an example of a method for transmitting transcodedcontent that can be used with various techniques and mechanisms of thepresent invention.

FIGS. 2-4 illustrate examples of systems that can be used with varioustechniques and mechanisms of the present invention.

FIG. 5 illustrates an example of a method for adaptive contenttranscoding.

FIG. 6 illustrates examples of encoding streams.

FIG. 7 illustrates one example of an exchange used with a media deliverysystem.

FIG. 8 illustrates one technique for generating a media segment.

FIG. 9 illustrates one example of a system.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Reference will now be made in detail to some specific examples of theinvention including the best modes contemplated by the inventors forcarrying out the invention. Examples of these specific embodiments areillustrated in the accompanying drawings. While the invention isdescribed in conjunction with these specific embodiments, it will beunderstood that it is not intended to limit the invention to thedescribed embodiments. On the contrary, it is intended to coveralternatives, modifications, and equivalents as may be included withinthe spirit and scope of the invention as defined by the appended claims.

For example, the techniques of the present invention will be describedin the context of fragments, particular servers and encoding mechanisms.However, it should be noted that the techniques of the present inventionapply to a wide variety of different fragments, segments, servers andencoding mechanisms. In the following description, numerous specificdetails are set forth in order to provide a thorough understanding ofthe present invention. Particular example embodiments of the presentinvention may be implemented without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail in order not to unnecessarily obscure the presentinvention.

Various techniques and mechanisms of the present invention willsometimes be described in singular form for clarity. However, it shouldbe noted that some embodiments include multiple iterations of atechnique or multiple instantiations of a mechanism unless notedotherwise. For example, a system uses a processor in a variety ofcontexts. However, it will be appreciated that a system can use multipleprocessors while remaining within the scope of the present inventionunless otherwise noted. Furthermore, the techniques and mechanisms ofthe present invention will sometimes describe a connection between twoentities. It should be noted that a connection between two entities doesnot necessarily mean a direct, unimpeded connection, as a variety ofother entities may reside between the two entities. For example, aprocessor may be connected to memory, but it will be appreciated that avariety of bridges and controllers may reside between the processor andmemory. Consequently, a connection does not necessarily mean a direct,unimpeded connection unless otherwise noted.

Overview

Content sent from a service provider to client machines may betranscoded into various encoding formats. Transcoding may be performedto ensure that the content is encoded in a format appropriate forpresentation on a client machine. A media system configured tocommunicate with client machines may collect information regarding thecapabilities and characteristics of devices requesting a media contentitem. Based on this information, the media system may dynamically selectoptions for transcoding media content items. For instance, the mediasystem may generate encodings to match the most common screenresolutions of devices requesting a media content item.

Example Embodiments

According to various embodiments, users may receive content from acontent management service. The content management service mayfacilitate the interaction of users with various types of contentservices. For instance, the content management service may provide auser interface for managing and accessing content from a number ofdifferent content sources. The interface may display content receivedvia a cable or satellite television connection, one or moreon-demand-video service providers such as Netflix or Amazon, and contentaccessible on local or network storage locations. In addition, theinterface may be used to access this content on any number of contentplayback devices.

According to various embodiments, the content management service mayreceive content from various sources, such as content service providers.Then, the content management service may transcode the content fortransmission to client machines. Content transcoding refers to anyprocess for changing data encoded in one format to data encoded in adifferent format. In particular embodiments, transcoding may involve alossy process that introduces generation loss into the resulting contentencoding. Alternately, or additionally, transcoding may involve alossless process such as lossless compression or decompression.

According to various embodiments, content sent from a service providerto client machines may be transcoded into various encoding formats for avariety of reasons. For instance, the content may be transcoded so thatcontent may be transmitted to client devices that do not support theoriginal format or that have a relatively limited storage capacity thatcan better handle a reduced file size. For instance, Cineon and DPXfiles have been widely used as a common format for digital cinema, butthe data size of a two-hour movie is about 8 terabytes, which is muchtoo large for streaming over currently available networks to moderncontent playback devices.

In particular embodiments, techniques and mechanisms described hereinmay be used for HTTP streaming and/or FMP4 streaming technologies.However, the techniques and mechanisms are generally applicable to awide range of video content technologies.

According to various embodiments, content may be received from a contentsource in an encoding at a relatively high resolution, such as 1900×1080pixels. However, many content playback devices may only support muchsmaller resolutions. In such situations, transmitting the originalcontent to the content playback devices would unnecessarily increase theamount of data transmitted. As well, the content playback device wouldneed to scale down the content for playback. Scaling down content forplayback, particularly for playback on a screen size that is anon-integer fraction of the screen resolution of the original encoding,can result in a fuzzy or distorted video.

In particular embodiments, a transcoded encoding may be encoded in ascreen resolution smaller than that of the original encoding. Forinstance, the source encoding may be encoded at a relatively highresolution, while the transcoded encoding may be presented in asignificantly smaller resolution. If an encoding is scaled at a clientmachine, then the resulting video presentation is likely to appear fuzzyor included visual artifacts that disrupt the appearance of the content.By performing this scaling at a server configured to perforintranscoding and with access to the source encoding, the content scalingmay be performed in a much more accurate way, resulting in a videopresentation that often appears noticeably sharper and clearer thanwould be the case if the content were scaled at a client machine. Inparticular embodiments, content may be scaled to a screen resolution ofone or more requesting devices. Alternately, content may be scaled to aninteger factor of such a screen resolution. According to variousembodiments, improvements in video presentation quality and/orreductions in data size may also be achieved with other types oftranscoding options, such as encoding format and frame rate.

According to various embodiments, adaptively creating video encodings toaccommodate the characteristics of requesting devices may in some casesprovide one or more advantages. For example, a larger number of devicesmay be supported by a media system. As another example, the set ofavailable content encodings may automatically change to reflect changesin the types of devices requesting the content without requiring usersto manually select settings for each encoding and/or each content item.As yet another example, the set of available content encodings mayautomatically change without requiring analysis of server logs toidentify changes in the most common device screen sizes. As stillanother example, transcoding may be performed in a manner thatefficiently uses computing resources, scaling the resource usage up anddown depending on the amount of transcoding need.

According to various embodiments, video encodings may be adaptivelycreated to provide content encodings for live video streams. Forinstance, a content provider may be transmitting video feed of a liveevent such as The Super Bowl. The content may be sent to the clientdevices in fragments or in a continuous stream. The media system mayanalyze requests for the content stream to determine what types ofdevices are requesting the content. Then, encoding of subsequentportions of the live stream may be dynamically updated to adjust to thetypes of requests received.

FIG. 1 shows a method 100 for transmitting transcoded content to aclient machine. According to various embodiments, the method 100 may beperformed at a media system, as discussed with respect to FIGS. 2-4. Themedia system may be operable to provide content management services to anumber of different client machines, as discussed herein. The contentmanagement service may provide content to users such as a user of theclient machine.

At 102, request for a content item is received from a client machine.According to various embodiments, the request may be received from anyclient machine capable of presenting a content item for playback. Forinstance, the client machine may be a television, laptop computer,desktop computer, tablet computer, mobile phone, or another type ofmobile computing device.

According to various embodiments, the requested content may be anycontent capable of being transmitted to the client machine for playback.The requested content may include video and/or audio content. Thecontent may be transmitted via a network such as the Internet, a cableor television cable network, or any other source. The content may bepre-recorded content, such as a movie or television program.Alternately, the content may be live content, such as a nightly newsprogram or a sports broadcast.

According to various embodiments, the content may be requested byvarious techniques. For example, a content item may be selected in anelectronic program guide or content navigation interface. As anotherexample, a content item may be requested for downloading by clicking ona link in a web browser. As yet another example, a content item may beautomatically requested, for instance in the case of an advertisementpresented on the client machine.

At 104, one or more hardware characteristics of the client machine areidentified. According to various embodiments, the hardwarecharacteristics may include any features or capabilities of hardwarepresent at or available to the client machine. The characteristics mayinclude, but are not limited to, a processor or memory resource, ascreen resolution, a screen size, or a communication capabilityassociated with the client machine.

At 106, one or more software characteristics of the client machine areidentified. According to various embodiments, the softwarecharacteristics may include any computer software programs orcapabilities present at or available to the client machine. Thecharacteristics may include, but are not limited to, content playbacksoftware, one or more content file types supported for playback, contentmanagement software, electronic program guide software, and/or contentcommunications software for receiving content at the client machine.

At 108, one or more data transmission characteristics for communicatingwith the client machine are identified. According to variousembodiments, the data transmission characteristics may be anyproperties, limitations, or procedures for transmitting information toor receiving information from the client machine. For example, theclient machine may be a computing device that has limited bandwidthavailable for receipt of content. As another example, the client machinemay be a mobile phone communicating via a network that places limits oncommunications bit rates. As yet another example, the client machine maybe configured to receive content via a unicast content transmissionmethod but not via a broadcast content transmission method.

According to various embodiments, the characteristics discussed withrespect to operations 104-108 may be determined in various ways. Forexample, information may be transmitted from the client machine alongwith the request received at operation 102. As another example, theclient machine may be linked with a content management account formanaging and accessing content. When the client machine is so linked,some or all of the information may be stored in association with thecontent management account so that when subsequent requests are receivedfrom the client machine, the client machine's characteristics may beretrieved.

At 110, a content encoding is selected for transmission to the clientmachine. According to various embodiments, content may be encoded invarious ways. For instance, different encodings of the same content itemmay differ in terms of frame rate, video bit rate, audio track bit rate,a number of audio channels, video encoding codec, audio encoding code,spacing between I-frames, or any other characteristics that may beselected, when transcoding content for playback.

According to various embodiments, a limited number of encodings of acontent item may be transcoded from a content source. The contentencodings may be created via a transcoding process. After contentencodings are created, the encodings may be stored for transmission tothe client machines by media servers. An example of a system operable tohandle requests for content, to transcode content for transmission toclient machines, and to store the encoded content is discussed withrespect to FIG. 2.

According to various embodiments, content encodings may be selected forcreation based on the information identified in operations 104-108. Forinstance, if many requests are received from devices with a particularscreen resolution, with similar bit rate requirements, and similar audioplayback capabilities, then a content encoding may be created to matchor approximate these characteristics. Techniques for transcoding contentfor storage so that the encoded content may be transmitted to clientmachines are discussed in additional detail with respect to FIG. 5.

At 112, instructions for receiving the selected content encoding aretransmitted to the client machine. According to various embodiments, theselected content encoding may be transmitted to the client machine inresponse to the request for the content, in particular embodiments, theclient machine may be sent instructions for retrieving the selectedcontent encoding from a different location. For instance, content itemsmay be available via a number of different media servers. When a contentencoding is selected, the client machine may be sent a uniform resourcelocator for retrieving the selected content encoding from one of themedia servers that has access to the stored the content encoding.

According to various embodiments, not all of the operations shown inFIG. 1 need be performed in every instance. For instance, in some casescertain types of information discussed in FIG. 1, such as software,hardware, or data transmission characteristics, may not be collected.

FIG. 2 shows a system 200 that can be used with various techniques andmechanisms of the present invention. According to various embodiments,the system 200 may be used to transcode content and provide encodedcontent to any number of client machines. The system 200 includes themedia system 202, which may communicate with the client machine 212. Themedia system 202 includes a frontend backend server 204, the mediaservers 206, the transcoding 208, and the encoded video storage system210.

According to various embodiments, the media system 202 may receiverequests for content, transcode content for presentation on clientmachines such as the client machine 212, and transmit the encodedcontent to the client machines. The client machine 212 may be any devicecapable of presenting content for playback. For instance, the clientmachine 212 may be a television, computer, or mobile computing devicesuch as a mobile phone.

According to various embodiments, the client machine 212 may transmit arequest to receive content to the frontend backend server 204. Thefrontend backend server may also identify information about the clientmachine such as the hardware, software, and/or communicationscapabilities of the client machine. For instance, the frontend backendserver may identify a screen resolution of the client machine.

According to various embodiments, the information about the clientmachine may be identified via a number of different techniques. Forexample, the information may be transmitted from the client machinealong with the request for content. As another example, the informationmay be associated with the client machine in a content managementaccount.

According to various embodiments, the content management account may beused to facilitate the transmission of content from a number ofdifferent sources to a number of different devices associated with thecontent management account. For example, a user may view content from acable or satellite television service provider, an on-demand videoservice provider such as Netflix or Amazon, and a local or networkstorage location via a connected user interface. As another example, theuser may view content from these various sources on devices that mayinclude, but are not limited to, a television, a desktop computer, alaptop computer, a tablet computer, and a mobile phone.

According to various embodiments, the frontend backend server 204 mayselect a content encoding for presentation on the client machine 212.For instance, a single content item may be transcoded into various typesof encodings for presentation at content devices. The content item maybe received from a content provider at a relatively high degree ofquality with a corresponding high resolution and large data size. Beforetransmitting the content to client devices, the content may betranscoded into an appropriate format. For instance, the resolution maybe decreased to a size suitable for mobile phones, laptops, televisions,or other devices that may have a relatively smaller screen size.

According to various embodiments, the frontend backend server 204 mayselect an available content encoding that closely matches thecapabilities of the client machine. For instance, if the client machinehas a screen resolution of 640×480 pixels, then the frontend backendserver 204 may select a transcoding that has a resolution close to640×480 pixels.

According to various embodiments, various encoding of a content item maybe available at one or more of the media servers 206. When the frontendbackend server 204 selects a encoding for presentation at the requestingclient machine 212, the frontend backend server 204 may facilitate thereceipt of the selected encoding by the client machine. For instance,the frontend backend server 204 may respond to the client machine'srequest with a uniform resource locator (URL) for retrieving the contentat one of the media servers 206. Then, the client machine 212 may usethe URL to retrieve the requested content.

According to various embodiments, the frontend backend server 204 maycollect information regarding the characteristics of client machinesrequesting the content. For instance, the frontend backend server 204may collect information such as the screen resolutions of the devices,the bandwidth capabilities of the devices, the software playbackcapabilities of the devices, or any other information.

Based on this information, the media system 202 may determine theencodings to create and store for transmission to client machines. Inparticular embodiments, the media system 202 may select encoding basedon the number of requests received from client machines of particulartypes. For instance, if a large number of requests for a content itemare received from devices having a screen resolution of 640×480 then thecontent item may be transcoded to an encoding having 640×480 pixels.When a particular set of encoding options are selected, for transcoding,the transcoding instructions may be sent to the transcoding clusters208.

According to various embodiments, transcoding may be performed by thetranscoding clusters 208. The transcoding clusters may receiveinstructions for transcoding a content item and then transcode thecontent in accordance with the instructions. For instance, theinstructions may specify an encoding resolution, an encoding file size,an encoding frame rate, or any other encoding options.

According to various embodiments, the transcoding clusters 208 mayinclude an type of computing device or devices operable to transcodevideo and/or audio content. For instance, the transcoding clusters 208may include distributing computers, mainframe computers, or any othertype of computing environments. In some cases, each of the transcodingclusters may have any number of transcoding nodes.

According to various embodiments, portions of the transcoding clusters208 may be provided by the content management provider associated withthe media system 202. Alternately, or additionally, portions of thetranscoding clusters 208 may be provided by a computing servicesprovider that provides on-demand computing services via a network suchas the Internet.

According to various embodiments, content items may be transcodingvarious ways. For example, in some cases a single transcoding clusterand/or transcoding node may perform all of the transcoding for a contentitem. As another example, in some cases the transcoding of a contentitem may be divided among a variety of content items. For instance, amovie may be split into different segments, and different segments maybe transcoded at different transcoding nodes. In particular embodiments,the techniques for transcoding content items may be strategicallydetermined based on factors such as the amount of content to betranscoded, the type of content to be transcoded, the cost and/orefficiency of various types of computing resources, the speed at whichvideo transcoding needs to be accomplished, or any other factors.

According to various embodiments, the computing resources active at thetranscoding clusters 208 may be scaled up or down based on the demandfor the resources. For instance, during some time intervals a largeamount of transcoding may be requested. During these time intervals,more clusters and/or nodes may be activated for transcoding. However,during other time intervals, a relatively smaller amount of transcodingmay be requested. During these other time intervals, clusters and/ornodes may be deactivated for transcoding.

According to various embodiments, by activating transcoding clusters ondemand, the usage of computing resources may be made more efficient. Forexample, in the case of on-demand computing resources, payment is oftencalculated based on usage so that lower usage of the computing resourcesresults in a lower cost. As another example, in the case of owned andmanaged computing resources, the cost of the maintaining the resourcesoften depends on usage, so that machines that are less used are lesslikely to require attention. Accordingly, varying the usage oftranscoding clusters and/or nodes based on demands may reduce the costof providing encoded content for presentation on client machines.

According to various embodiments, content items that have beentranscoded may be stored on the encoded video storage system 210. Theencoded video storage system 210 may contain any number of hard drivesor other storage media for storing the encoded content. The encodedcontent may be made available to the media servers 206 for transmissionto the client machine 212 or other client machines. In particularembodiments, the encoded video storage system 210 may be incorporatedinto the media servers 206. For instance, different media servers mayhave different content encodings available for transmission to theclient machines. Then, the frontend backend server 204 may provide theclient machine 212 with an address to content at an appropriate one ofthe media servers 206 known to host the content encoding selected by thefrontend backend server 201 that corresponds to the content itemrequested by the client machine 212.

According to various embodiments, a media system may include elementsnot shown in FIG. 2. For example, the media system may include a cachingservice that stores content provided by the media servers. Then, whencontent is requested, the content may be transmitted from the cachingservice if the content is cached, which may help reduce the computingload on the media servers.

FIG. 3 is a diagrammatic representation illustrating one example of afragment or segment system 301 associated with a content server that maybe used in a broadcast and unicast distribution network. Encoders 305receive media data from satellite, content libraries, and other contentsources and sends RTP multicast data to fragment writer 309. Theencoders 305 also send session announcement protocol (SAP) announcementsto SAP listener 321. According to various embodiments, the fragmentwriter 309 creates fragments for live streaming, and writes files todisk for recording. The fragment writer 309 receives RTP multicaststreams from the encoders 305 and parses the streams to repackage theaudio/video data as part of fragmented MPEG-4 files. When a new programstarts, the fragment writer 309 creates a new MPEG-4 file on fragmentstorage and appends fragments. In particular embodiments, the fragmentwriter 309 supports live and/or DVR configurations.

The fragment server 311 provides the caching layer with fragments forclients. The design philosophy behind the client/server applicationprogramming interface (API) minimizes round trips and reduces complexityas much as possible when it comes to delivery of the media data to theclient 315. The fragment server 311 provides live streams and/or DVRconfigurations.

The fragment controller 307 is connected to application servers 303 andcontrols the fragmentation of live channel streams. The fragmentationcontroller 307 optionally integrates guide data to drive the recordingsfor a global/network DVR. In particular embodiments, the fragmentcontroller 307 embeds logic around the recording to simplify thefragment writer 309 component. According to various embodiments, thefragment controller 307 will run on the same host as the fragment writer309. In particular embodiments, the fragment controller 307 instantiatesinstances of the fragment writer 309 and manages high availability.

According to various embodiments, the client 315 uses a media componentthat requests fragmented MPEG-4 files, allows trick-play, and managesbandwidth adaptation. The client communicates with the applicationservices associated with HTTP proxy 313 to get guides and present theuser with the recorded content available.

FIG. 4 illustrates one example of a fragmentation system 401 that can beused for video-on-demand (VoD) content. Fragger 403 takes an encodedvideo clip source. However, the commercial encoder does not create anoutput file with minimal object oriented framework (MOOF) headers andinstead embeds all content headers in the movie file (MOOV). The fraggerreads the input file and creates an alternate output that has beenfragmented with MOOF headers, and extended with custom headers thatoptimize the experience and act as hints to servers.

The fragment server 411 provides the caching layer with fragments forclients. The design philosophy behind the client/server API minimizesround trips and reduces complexity as much as possible when it comes todelivery of the media data to the client 415. The fragment server 411provides VoD content.

According to various embodiments, the client 415 uses a media componentthat requests fragmented MPEG-4 files, allows trick-play, and managesbandwidth adaptation. The client communicates with the applicationservices associated with HTTP proxy 413 to get guides and present theuser with the recorded content available.

FIG. 5 illustrates an example of a method 500 for adaptive contenttranscoding. According to various embodiments, the method 500 may beperformed at a media system, as discussed with respect to FIGS. 2-4. Themethod 500 may analyze information regarding client device capabilitiesand use the information to select Options for transcoding the content.The types of content encodings stored for transmission to clientmachines may be customized so that encodings are created to match thecharacteristics of more popular devices.

At 502, a request to conduct adaptive content transcoding for a contentitem is received. According to various embodiments, the request toconduct adaptive content transcoding may be generated automatically orin response to user input. For example, a request to conduct adaptivecontent transcoding for a content item may be automatically generatedwhen the content item is first added to the media system. As anotherexample, a request to conduct transcoding may be generated at regularintervals. As yet another example, a request to conduct transcoding maybe generated in response to the receipt of a large number of requestsfor the item, particularly if the requests are from devices havingcharacteristics that are not well supported by existing encodings. Asstill another example, a request to conduct transcoding may be generatedby a user such as a system administrator.

According to various embodiments, different types of encodings may becreated for different content items. For instance, some content may bemore often requested for playback on mobile, handheld devices thattypically have relatively small screen sizes. However, other content maybe more often requested for playback on devices that typically haverelatively large screens, such as televisions or desktop computers.

At 504, information regarding characteristics of client devices iscollected. According to various embodiments, the information collectedmay include, but is not limited to, the information discussed withrespect to operations 104-108 shown in FIG. 1. In some cases, theinformation may be collected when client devices transmit requests forthe content item. Alternately, or additionally, the information may becollected when devices are registered with the content managementsystem.

In particular embodiments, the information may describe devices thathave requested the content item being transcoded. Alternately, oradditionally, the information may describe other devices and may be usedto predict the preferred encodings for the content item. For example,the content item may be a particular episode of a television series. Inthis case, the content item may not yet have been requested for playbackif it has not yet been released. However, information may be collectedregarding client devices that have requested other episodes in thetelevision series. As another example, the content item may be a movie,for instance a drama. In this case, information may be collectedregarding similar movies to select an encoding or encodings for thecontent item.

At 506, options for transcoding content are selected based on thecharacteristics identified in operation 504. According to variousembodiments, various types of options may be selected for transcodingcontent. These options may include, but are not limited to, a video bitrate, an audio track bit rate, a number of audio channels, an encodingformat, a spacing between video I-frames, a video screen resolutionsize, data size, or any other transcoding options supported by the videotranscoding system.

According to various embodiments, various techniques may be used toselect options for transcoding content. For example, content may beencoded to match characteristics of requesting client devices when thenumber of requests from a type of client devices meets a designatedthreshold number or percentage, such as 10%. As another example, adesignated number of encodings may be created for a content item, andthe properties for each of these encodings may be selected toeffectively serve as many of the requesting devices as possible.

According to various embodiments, the options for transcoding contentand/or the conditions in which a new encoding is created may bedesignated via a configurable rule set. The rule set may be created orsupplied by a user such as a system administrator. Alternately, the ruleset may be dynamically created based on various criteria.

At 508, the content is transcoded based on the selected, options.According to various embodiments, transcoding the content may involveretrieving a source encoding of the content. The source encoding may bereceived from a content provider and stored for later encoding. Inparticular embodiments, the source encoding may be a high fidelityencoding of relatively large file size.

According to various embodiments, the source encoding may be transcodedbased on the options selected at operation 506. Transcoding the sourceencoding may involve applying one or more algorithms, transformations,or other data processing operations to transform the data encoded in thesource encoding to a format in accordance with the options selected atoperation 506. In particular embodiments, this process may be somewhat“lossy,” resulting in an encoding that contains less information thanthe original encoding. However, in some cases the transcoding processmay be lossless.

In particular embodiments, the transcoded encoding may be significantlysmaller in data size than the source encoding. The smaller data size maymake the encoding easier to transmit to a client machine for playbackand easier for the client machine to store, process, and present.

In particular embodiments, the transcoded encoding may be presented in ascreen resolution smaller than that of the original encoding. Forinstance, the source encoding may be encoded at a relatively highresolution, while the transcoded encoding may be presented in asignificantly smaller resolution. If an encoding is scaled, at a clientmachine, then the resulting video presentation is likely to appear fuzzyor included visual artifacts that disrupt the appearance of the content.By performing this scaling at a server configured to perform transcodingand with access to the source encoding, the content scaling may beperformed in a much more accurate way, resulting in a video presentationthat often appears noticeably sharper and clearer than would be the caseif the content were scaled at a client machine.

According to various embodiments, various types of computing frameworksmay be used to transcode content. These frameworks may include, but arenot limited to: grid array computers, distributed computers, computersmanaged by the media system, and on-demand computers accessible via anetwork such as the Internet. In particular embodiments, transcoding maybe performed at one or more transcoding clusters, which each may havecomputing resources divided, among a number of transcoding nodes.

According to various embodiments, computer resources may be activatedand deactivated for transcoding to efficiently accommodate the demandfor the resources. In some cases, a content item may be encoded all atonce. In other cases, a content item may be broken into segments andencoded separately, which may use more computing resources but use themfor a smaller length of time.

At 510, the encoded content is stored for transmission to clientmachines. In particular embodiments, the encoded content may be storedat the encoded video storage system 210 discussed with respect to FIG.2. When the encoded content is stored, the media servers 206 may beinformed that the content is available. Then, the media servers 206 maytransmit the encoded video to a client machine that requests it.

According to various embodiments, encodings may be stored for a lengthof time for transmitting to client devices. The length of time forstoring each encoding may be strategically determined based on factorsthat may include, but are not limited to, the availability of storagespace, the frequency or number of requests for the content item, thefrequency or number of requests thr the encoding, the frequency ornumber of requests for other encodings, and the number of otherencodings of the content item.

At 512, a determination is made as to whether to create additionalencodings of the content. According to various embodiments, thedetermination is made as to whether to create encodings may be madebased on various factors. For example, content items that are requestedmore often may be allotted a higher number of encodings. As anotherexample, content items that are requested from a larger variety ofdevices, such as devices that vary in screen size, may be allotted ahigher number of encodings. As yet another example, content encodingsmay be created for device characteristics that exceed a designatedthreshold number of requests for the content item. As still anotherexample, the determination may be based at least in part on anavailability of computing resources, storage space, encoding size, orany other factors.

FIG. 6 illustrates examples of files stored by the fragment writer.According to various embodiments, the fragment writer is a component inthe overall fragmenter. It is a binary that uses command line argumentsto record a particular program based on either NIP time from the encodedstream or wallclock time. In particular embodiments, this isconfigurable as part of the arguments and depends on the input stream.When the fragment writer completes recording a program, it exits. Forlive streams, programs are artificially created to be short timeintervals e.g. 5-15 minutes in length.

According to various embodiments, the fragment writer command linearguments are the SDP file of the channel to record, the start time, endtime, name of the current and next output files. The fragment writerlistens to RTP traffic from the live video encoders and rewrites themedia data to disk as fragmented MPEG-4. According to variousembodiments, media data is written as fragmented MPEG-4 as defined inMPEG-4 part 12 (ISO/IEC 14496-12). Each broadcast show is written todisk as a separate file indicated by the show ID (derived from EPG).Clients include the show ID as part of the channel name when requestingto view a prerecorded show. The fragment writer consumes each of thedifferent encodings and stores them as a different MPEG-4 fragment.

In particular embodiments, the fragment writer writes the RTP data for aparticular encoding and the show ID field to a single file. Inside thatfile, there is metadata information that describes the entire file (MOOVblocks). Atoms are stored as groups of MOOF/MDAT pairs to allow a showto be saved as a single file. At the end of the file there is randomaccess information that can be used to enable a client to performbandwidth adaptation and trick play functionality.

According to various embodiments, the fragment writer includes an optionwhich encrypts fragments to ensure stream security during the recordingprocess. The fragment writer will request an encoding key from thelicense manager. The keys used are similar to that done for DRM. Theencoding format is slightly different where MOOF is encoded. Theencryption occurs once so that it does not create prohibitive costsduring delivery to clients.

The fragment server responds to HTTP requests for content. According tovarious embodiments, it provides APIs that can be used by clients to getnecessary headers required to decode the video and seek any desired timeframe within the fragment and APIs to watch channels live. Effectively,live channels are served from the most recently written fragments forthe show on that channel. The fragment server returns the media header(necessary for initializing decoders), particular fragments, and therandom access block to clients. According to various embodiments, theAPIs supported allow for optimization where the metadata headerinformation is returned to the client along with the first fragment. Thefragment writer creates a series of fragments within the file. When aclient requests a stream, it makes requests for each of these fragmentsand the fragment server reads the portion of the file pertaining to thatfragment and returns it to the client.

According to various embodiments, the fragment server uses a REST APIthat is cache-friendly so that most requests made to the fragment servercan be cached. The fragment server uses cache control headers and ETagheaders to provide the proper hints to caches. This API also providesthe ability to understand where a particular user stopped playing and tostart play from that point (providing the capability for pause on onedevice and resume on another).

In particular embodiments, client requests for fragments follow thefollowing format:http://{HOSTNAME}/frag/{CHANNEL}/{BITRATE}/[{ID}/]{COMMAND}[/{ARG}] e.g.http://frag.hosttv.com/frag/1/H8QVGAH264/1270059632.mp4/fragment/42.According to various embodiments, the channel name will be the same asthe backend-channel name that is used as the channel portion of the SDPfile. VoD uses a channel name of “vod”. The BITRATE should follow theBITRATE/RESOLUTION identifier scheme used for RTP streams. The ID isdynamically assigned. For live streams, this may be the UNIX timestamp;for DVR, this will be unique ID for the show; for VoD this will be theasset ID. The ID is optional and not included in LIVE command requests.The command and argument are used to indicate the exact command desiredand any arguments. For example, to request chunk 42, this portion wouldbe “fragment/42”.

The URL format makes the requests content delivery network (CDN)friendly because the fragments will never change after this point so twoseparate clients watching the same stream can be serviced using a cache.In particular, the head end architecture leverages this to avoid toomany dynamic requests arriving at the Fragment Server by using an HTTPproxy at the head end to cache requests.

According to various embodiments, the fragment controller is a daemonthat runs on the fragmenter and manages the fragment writer processes. Aconfigured filter that is executed by the fragment controller can beused to generate the list of broadcasts to be recorded. This filterintegrates with external components such as a guide server to determinewhich shows to record and which broadcast ID to use.

According to various embodiments, the client includes an applicationlogic component and a media rendering component. The application logiccomponent presents the user interface (UI) for the user, communicates tothe front-end server to get shows that are available for the user, andauthenticates the content. As part of this process, the server returnsURLs to media assets that are passed to the media rendering component.

In particular embodiments, the client relies on the fact that eachfragment in a fragmented MP4 file has a sequence number. Using thisknowledge and a well-defined URL structure for communicating with theserver, the client requests fragments individually as if it was readingseparate files from the server simply by requesting URLs for filesassociated with increasing sequence numbers. In some embodiments, theclient can request files corresponding to higher or lower bit ratestreams depending on device and network resources.

Since each file contains the information needed to create the URL forthe next file, no special playlist files are needed, and all actions(startup, channel change, seeking) can be performed with a single HTTPrequest. After each fragment is downloaded, the client assesses, amongother things, the size of the fragment and the time needed to download,it in order to determine if downshifting is needed or if there is enoughbandwidth available to request a higher bit rate.

Because each request to the server looks like a request to a separatefile, the response to requests can be cached in any HTTP Proxy, or bedistributed over any HTTP based content delivery network CDN.

FIG. 7 illustrates an interaction for a client receiving a media streamsuch as a live stream. The client starts playback when fragment 71 playsout from the server. The client uses the fragment number on that it canrequest the appropriate subsequent file fragment. An application such asa player application 707 sends a request to mediakit 705. The requestmay include a base address and bit rate. The mediakit 705 sends an HTTPget request to caching layer 703. According to various embodiments, thelive response is not in cache, and the caching layer 703 forwards theHTTP get request to a fragment server 701. The fragment server 701performs processing and sends the appropriate fragment to the cachinglayer 703 which forwards to the data to mediakit 705.

The fragment may be cached for a short period, of time at caching layer703. The mediakit 705 identifies the fragment number and determineswhether resources are sufficient to play the fragment. In some examples,resources such as processing or bandwidth resources are insufficient.The fragment may not have been received quickly enough, or the devicemay be having trouble decoding the fragment with sufficient speed.Consequently, the mediakit 705 may request a next fragment having adifferent data rate. In some instances, the mediakit 705 may request anext fragment having a higher data rate. According to variousembodiments, the fragment server 701 maintains fragments for differentquality of service streams with timing synchronization information toallow for timing accurate playback.

The mediakit 705 requests a next fragment using information from thereceived fragment. According to various embodiments, the next fragmentfor the media stream may be maintained on a different server, may have adifferent bit rate, or may require different authorization. Cachinglayer 703 determines that the next fragment is not in cache and forwardsthe request to fragment server 701. The fragment server 701 sends thefragment to caching layer 703 and the fragment is cached for a shortperiod of time. The fragment is then sent to mediakit 705.

FIG. 8 illustrates a particular example of a technique for generating amedia segment. According to various embodiments, a media stream isrequested by a device at 801. The media stream may be a live stream,media clip, media file, etc. The request for the media stream may be anHTTP GET request with a baseurl, bit rate, and file name. At 803, themedia segment is identified. According to various embodiments, the mediasegment may be a 35 second sequence from an hour long live media stream.The media segment may be identified using time indicators such as astart time and end time indicator. Alternatively, certain sequences mayinclude tags such as fight scene, car chase, love scene, monologue,etc., that the user may select in order to identify a media segment. Instill other examples, the media stream may include markers that the usercan select. At 805, a server receives a media segment indicator such asone or more time indicators, tags, or markers. In particularembodiments, the server is a snapshot server, content server, and/orfragment server. According to various embodiments, the server delineatesthe media segment maintained in cache using the segment indicator at807. The media stream may only be available in a channel buffer. At 809,the server generates a media file using the media segment maintained incache. The media file can then be shared by a user of the device at 811.In some examples, the media file itself is shared while in otherexamples, a link to the media file is shared.

FIG. 9 illustrates one example of a server. According to particularembodiments, a system 900 suitable for implementing particularembodiments of the present invention includes a processor 901, a memory903, an interface 911, and a bus 915 (e.g., a PCI bus or otherinterconnection fabric) and operates as a streaming server. When actingunder the control of appropriate software or firmware, the processor 901is responsible for modifying and transmitting live media data to aclient. Various specially configured devices can also be used in placeof a processor 901 or in addition to processor 901. The interface 911 istypically configured to send and receive data packets or data segmentsover a network.

Particular examples of interfaces supported include Ethernet interfaces,frame relay interfaces, cable interfaces, DSL interfaces, token ringinterfaces, and the like. In addition, various very high-speedinterfaces may be provided, such as fast Ethernet interfaces, GigabitEthernet interfaces, ATM interfaces, HSSI interfaces, POS interfaces,FDDI interfaces and the like. Generally, these interfaces may includeports appropriate for communication with the appropriate media. In somecases, they may also include an independent processor and, in someinstances, volatile RAM. The independent processors may controlcommunications-intensive tasks such as packet switching, media controland management.

According to various embodiments, the system 900 is a server that alsoincludes a transceiver, streaming buffers, and a program guide database.The server may also be associated with subscription management, loggingand, report generation, and monitoring capabilities. In particularembodiments, the server can be associated with functionality forallowing operation with mobile devices such as cellular phones operatingin a particular cellular network and providing subscription managementcapabilities. According to various embodiments, an authentication moduleverifies the identity of devices including mobile devices. A logging andreport generation module tracks mobile device requests and associatedresponses. A monitor system allows an administrator to view usagepatterns and system availability. According to various embodiments, theserver handles requests and responses for media content relatedtransactions while a separate streaming server provides the actual mediastreams.

Although a particular server is described, it should be recognized thata variety of alternative configurations are possible. For example, somemodules such as a report and logging module and a monitor may not beneeded on every server. Alternatively, the modules may be implemented onanother device connected to the server. In another example, the servermay not include an interface to an abstract buy engine and may in factinclude the abstract buy engine itself. A variety of configurations arepossible.

In the foregoing specification, the invention has been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the invention as set forth in theclaims below. Accordingly, the specification and figures are to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope ofinvention.

The invention claimed is:
 1. A method comprising: receiving, at aserver, a plurality of requests from client devices to access a livestreaming media content item for playback at the client devices, theclient devices including a designated client device, each of the clientdevices having associated therewith device characteristic informationthat describes one or more characteristics of the client device;transmitting a first portion of the live streaming media content itemencoded in a first encoding format to the designated client device;identifying a device characteristic that describes a portion of theclient devices, the portion of the client devices meeting a thresholdvalue for creating a media content encoding item, the portion of theclient devices including the designated client device; transcoding amedia content source item corresponding to the requested live streamingmedia content item to create a live streaming media content encodingitem encoded in a second encoding format, the live streaming mediacontent encoding item being encoded to match the identified devicecharacteristic; and transmitting a second portion of the live streamingmedia content item encoded in the second encoding format to thedesignated client device, the second portion of the live streaming mediaincluding the live streaming media content encoding item.
 2. The methodrecited in claim 1, wherein the identified device characteristiccomprises a screen resolution of a display screen at the portion of theclient devices.
 3. The method recited in claim 1, wherein the identifieddevice characteristic is a characteristic selected from the groupconsisting of: a network connection speed for communicating with theportion of the client devices, a device processor common to the portionof the client devices, and a number of colors supported by displayscreens at the portion of the client devices.
 4. The method recited inclaim 1, the method further comprising: storing the media contentencoding item on a storage system for transmission to selected ones ofthe client devices.
 5. The method recited in claim 1, wherein the serveris operable to provide content management services to the clientdevices, the content management services including the providing ofon-demand video content to the client devices.
 6. The method recited inclaim 1, the method further comprising: selecting, for each of theclient devices, a respective one of a plurality of media contentencoding items for presenting the requested media content item on theclient devices; and transmitting to each of the client devices aninstruction for receiving the respective media content encoding item. 7.The method recited in claim 1, wherein the threshold value comprises adesignated number of requests.
 8. The method recited in claim 1, whereinthe identified device characteristic is a characteristic selected fromthe group consisting of: a number of audio channels, an audio track bitrate, a video bit rate, a video frame rate, an encoding format, and aspacing between video I-frames.
 9. A system comprising: a communicationsinterface operable to receive a plurality of requests from clientdevices to access a live streaming media content item for playback atthe client devices, the client devices including a designated clientdevice, each of the client devices having associated therewith devicecharacteristic information that describes one or more characteristics ofthe client device, and to transmit a first portion of the live streamingmedia content item encoded in a first encoding format to the designatedclient device; a processor operable to identify a device characteristicthat describes a portion of the client devices, the portion of theclient devices meeting a threshold value for creating a media contentencoding item, the portion of the client devices including thedesignated client device; a transcoding module operable to transcode alive streaming media content source item corresponding to the requestedmedia content item to create a live streaming media content encodingitem encoded in a second encoding format, the live streaming mediacontent encoding item being encoded to match the identified devicecharacteristic, wherein the communications interface is operable totransmit a second portion of the live streaming media content itemencoded in the second encoding format to the designated client device,the second portion of the live streaming media including the livestreaming media content encoding item.
 10. The system recited in claim9, wherein the identified device characteristic comprises a screenresolution of a display screen at the portion of the client devices. 11.The system recited in claim 9, wherein the identified devicecharacteristic is a characteristic selected from the group consistingof: a network connection speed for communicating with the portion of theclient devices, a device processor common to the portion of the clientdevices, and a number of colors supported by display screens at theportion of the client devices.
 12. The system recited in claim 9, thesystem further comprising: a storage system operable to store the mediacontent encoding item for transmission to selected ones of the clientdevices.
 13. The system recited in claim 9, wherein the server isoperable to provide content management services to the client devices,the content management services including the providing of on-demandvideo content to the client devices.
 14. The system recited in claim 9,wherein the processor is further operable to select, for each of theclient devices, a respective one of a plurality of media contentencoding items for presenting the requested media content item on theclient devices, and wherein the communications interface is furtheroperable to transmit to each of the client devices an instruction forreceiving the respective media content encoding item.
 15. The systemrecited in claim 9, wherein the threshold value comprises a designatednumber of requests.
 16. The system recited in claim 9, wherein theidentified device characteristic is a characteristic selected from thegroup consisting of: a number of audio channels, an audio track bitrate, a video bit rate, a video frame rate, an encoding format, and aspacing between video I-frames.
 17. One or more non-transitory computerreadable media having instructions stored thereon for performing amethod, the method comprising: receiving, at a server, a plurality ofrequests from client devices to access a live streaming media contentitem for playback at the client devices, the client devices including adesignated client device, each of the client devices having associatedtherewith device characteristic information that describes one or morecharacteristics of the client device; transmitting a first portion ofthe live streaming media content item encoded in a first encoding formatto the designated client device; identifying a device characteristicthat describes a portion of the client devices, the portion of theclient devices meeting a threshold value for creating a media contentencoding item, the portion of the client devices including thedesignated client device; transcoding a media content source itemcorresponding to the requested live streaming media content item tocreate a live streaming media content encoding item encoded in a secondencoding format, the live streaming media content encoding item beingencoded to match the identified device characteristic; and transmittinga second portion of the live streaming media content item encoded in thesecond encoding format to the designated client device, the secondportion of the live streaming media including the live streaming mediacontent encoding item.
 18. The one or more non-transitory computerreadable media recited in claim 17, wherein the identified devicecharacteristic comprises a screen resolution of a display screen at theportion of the client devices.
 19. The one or more non-transitorycomputer readable media recited in claim 17, wherein the identifieddevice characteristic is a characteristic selected from the groupconsisting of: a network connection speed for communicating with theportion of the client devices, a device processor common to the portionof the client devices, and a number of colors supported by displayscreens at the portion of the client devices.
 20. The one or morenon-transitory computer readable media recited in claim 17, the methodfurther comprising: storing the media content encoding item on a storagesystem for transmission to selected ones of the client devices.